Excitation of Earth's continuous free oscillations by atmosphere-ocean-seafloor coupling
Excitation of Earth's continuous free oscillations by atmosphere-ocean-seafloor coupling
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DOI：
10.1038/nature02942
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发表时间：
2004-09-30
期刊：
影响因子：
64.8
通讯作者：
Romanowicz, B
中科院分区：
文献类型：
--
作者：
Rhie, J;Romanowicz, B
地球经历了连续的振荡，在没有重大地震的日子里，在2-7 MHz(参考文献1，2)的频率范围内的地震记录中一致地发现了自由振荡峰值。这种“嗡嗡声”的每日激发水平相当于5.75至6.0级地震(3，4级)，这不能用小地震(1，3级)的贡献相加来解释。由于慢地震或无声地震已被排除为嗡嗡声的来源(4)(除少数个别情况外(5))，大气中的湍流运动或海洋中的过程被援引作为激发机制(3，6-8)。我们开发了一种基于阵列的方法来检测和定位嗡嗡声的激发源。我们的结果表明，地球嗡嗡声在北半球冬季主要起源于北太平洋，在南半球冬季主要起源于南太平洋。我们的结论是，地球的嗡嗡声是由大气、海洋和海底之间的相互作用产生的，可能是通过将风暴能量转化为与海底地形相互作用的海洋亚重力波而产生的。
The Earth undergoes continuous oscillations, and free oscillation peaks have been consistently identified in seismic records in the frequency range 2 - 7 mHz (refs 1, 2), on days without significant earthquakes. The level of daily excitation of this 'hum' is equivalent to that of magnitude 5.75 to 6.0 earthquakes(3,4), which cannot be explained by summing the contributions of small earthquakes(1,3.) As slow or silent earthquakes have been ruled out as a source for the hum(4) ( except in a few isolated cases(5)), turbulent motions in the atmosphere or processes in the oceans have been invoked(3,6-8) as the excitation mechanism. We have developed an array-based method to detect and locate sources of the excitation of the hum. Our results demonstrate that the Earth's hum originates mainly in the northern Pacific Ocean during Northern Hemisphere winter, and in the Southern oceans during Southern Hemisphere winter. We conclude that the Earth's hum is generated by the interaction between atmosphere, ocean and sea floor, probably through the conversion of storm energy to oceanic infragravity waves that interact with seafloor topography.